DES MOINES, Iowa (AP) — The medical director for the Iowa Department of Public Health is warning against the tapeworm diet.

In her weekly email to public health workers around Iowa, Dr. Patricia Quinlisk recounted a recent incident:

A physician sought the department’s help for a patient who said she’d swallowed a tapeworm she’d bought over the Internet. The woman was hoping the parasite would help her lose weight.

Quinlisk says hucksters sold tapeworm eggs in pill form as a weight-loss aid a century ago. She says ingesting them “is extremely risky and can cause a wide range of undesirable side effects, including rare deaths.”

Tapeworms can live for years in the intestines and grow to several feet long. They can be accidentally ingested in undercooked meat.